The present invention relates to a box blank and a method of forming same.
Containers, such as boxes, are ubiquitous and essential for storage, packaging and transport of various goods and products. Cardboard boxes are generally preferred over boxes made of other materials such as plastic and various blanks for transport of cargo because they are lighter, less bulky and recyclable. Such boxes may also be formed as a blank, to minimize volume when empty and which is assemblable to form the box. However, the inherent disadvantages of cardboard boxes are that they are prone to damage and have weak hinges and are thereby unsuitable for stacking and containing heavy loads. Moreover, cardboard boxes normally require adhesive taping of the flaps covering the top of the box to prevent therm from caving in or opening up.
It is an object of the invention to provide an improved box blank.
According to the invention in the first aspect there is provided a box blank formed from plastics material and comprising a plurality of hinge elements connecting a plurality of panels for forming sides of the box, the hinge elements and panels being formed from different plastics material.
The hinge elements are preferably formed by plastics material having greater toughness but less rigidity than the plastics material forming the panels to provide structure advantages for both components which could not be achieved with a box blank of a single material.
The hinge elements are further preferably formed from a plastics material having a melt index less than the material from which the panels are formed and have a plurality of projections formed thereon.
According to the invention in the second aspect there is provided a method of forming a box blank comprising the steps of: forming a net of hinge elements of a first plastics material; and forming panels of a second plastics material in the spaces between elements of the net.
Preferably the net is placed in an injection mould with the second plastics material being injected into said spaces to form the panels. Preferably the injection moulding process is separately controlled for each panel so that the panels are formed evenly.
The net is preferably formed from the first plastics material having a melt index less than the melt index of the second plastics material so that the second plastics material when injected melts the skin of the first plastics material so that the plastics material fuse together to form the box blank.
Preferably the net is provided with a plurality of projections formed thereon which act, firstly, to help reduce surface tension effects when the second material is injected and, form islands to which the second material can attach itself. Furthermore, the projections project slightly above the level of the panels once formed and when formed from a less rigid material, create an anti-slide panel to assist in frictional contact between the boxes when stacked.
According to the invention in the third aspect there is provided a box blank comprising a plurality of panels connected by hinge elements, the panels including structural panels forming the sides of the box and load bearing panels, the load bearing panels being connected to the structural panels by hinge elements formed parallel to the intended direction of load bearing support provided by the load bearing panels.
With the box blank constructed in accordance with the third, aspect of the invention, the load bearing panels provided additional columnal support to the structural panels without an intervening hinge element in the direction of intended, load support which might be subject to stress leading to consequent failure.